Mixing and conveying apparatus

ABSTRACT

Apparatus for mixing and conveying at least two materials, particularly liquid materials together forming a two or multicomponent resin system, comprising a mixing chamber, a mixing and conveying worm located in the chamber, and two feed passages communicating with the chamber through orifices which are obturable by a common sealing piston, wherein in order to ensure simultaneous opening and closing of the orifices, they are located in a plane normal to the direction of travel of the piston. In one embodiment, the piston is carried on and axially movable with the worm, the orifices being formed in the wall of the mixing chamber. Alternatively, the orifices may open into a preliminary chamber, itself opening into the mixing chamber, and in which the piston moves. The leading surface of the piston in the closing position forms a part of the wall of the mixing chamber.

United States Patent [191 Schwab et a1.

[ Sept. 25, 1973 MIXING AND CONVEYING APPARATUS [73] Assignee: SemperitAktiengesellschaft,

Hauptstrasse, Austria [22] Filed: Dec. 15, 1970 [21] Appl. No.: 98,407

[30] Foreign Application Priority Data Dec. 23, 1969 Austria A 12030/69[56] References Cited UNITED STATES PATENTS 3,608,781 9/1971 Flynn222/136 X 3,102,004 8/1963 Grintz 259/7 X 11/1962 Carter ..259/25 2/1962Allen 137/6254 X Primary Examiner--John Petrakes Assistant Examiner-AlanI. Cantor Attorney-Emest F. Marmorek 1 ABSTRACT Apparatus for mixing andconveying at least two materials, particularly liquid materials togetherforming a two or multi-component resin system, comprising a mixingchamber, a mixing and conveying worm located in the chamber, and twofeed passages communicating with the chamber through orifices which areobturable by a common sealing piston, wherein in order to ensuresimultaneous opening and closing; of the orifices, they are located in aplane normal to the direction of travel of the piston. In oneembodiment, the piston is carried on and axially movable with the worm,the orifices being formed in the wall of the mixing chamber.Alternatively, the orifices may open into a preliminary chamber, itselfopening into the mixing chamber, and in which the piston moves. Theleading surface'of the piston in the closing position forms a part ofthe wall of the mixing chamber.

12 Claims, 8 DrawingFigures PATENTED 2 73 SHEET 2 BF 2 MIXING ANDCONVEYING APPARATUS BACKGROUND OF THE INVENTION The present inventionrelates to apparatus for mixing and conveying at least two materails,particularly liquid materials, in particular materials together forminga two-component or multicomponent synthetic resin systern.

Mixing and conveying apparatus is known comprising at least one mixingchamber, a conveyor and stirrer worm and at least two obturable feedpassages. In known devices of this kind, two or more passages open intothe mixing chamber, each passage having its own shut-off device. In thecase of reactive synthetic resin systems, in particualr polyurethanesystems, an accurate mixing ratio is essential since otherwisesubstantial differences in the properties of the material formed areencountered. It is necessary, therefore, to introduce the individualcomponents into a mixing chamber in a very accurately dosed manner, thesubstances then being mixed in and moved out of the mixing chamber bythe worm. By adjusting the shut-off devices, it is possible to arrangefor a predetermined quantity of the components to flow into the mixingchamber per unit time. The shut-off valves must as far as possible bothopen and close simultaneously, in order to prevent any lead or lag onthe part of a component. In a system employing pneumatic or hydraulicoperation of the valves, this simultaneous opening and closing cannotalways be achieved since frequently differences in adjustment or thepresence of foreign bodies can cause one servo cylinder to operate moreslowly than the other. If the valves are to be mechanically coupled,then very precise and elaborate devices are needed and these again donot operate totally without play.

SUMMARY OF THE INVENTION According to the invention, there is providedapparatus for mixing and conveying at least two materials, particularlyliquid materials forming together a twocomponent or multi-componentsynthetic resin system, comprising a mixing chamber, agitating andconveying means located within said mixing chamber, and two feedpassages leading to said mixing chamber, said passages having respectiveorifices opening to said chamber and obturable by movement of a commonsealing piston, said orifices lying in a plane normal to the directionof travel of said piston.

In one embodiment of the invention, the piston is arranged to form partof the worm.

In another embodiment of the invention, the piston is arranged in apreliminary mixing chamber opening into the mixing chamber, the feedpassage orifices being formed in the wall of this auxiliary chamber andthe leading surface of the piston forms part of the mixing chamber wallwhen in the position to close the orifices.

In this embodiment, as the piston in the preliminary chamber is movedaway from the mixing chamber, it simultaneously opens the orifices ofthe feed passages. The components can then flow into the preliminarychamber where they immediately undergo preliminary mixing and thencepass into the mixing chamber proper. When the piston moves in theopposite direction, the openings are closed simultaneously and thematerial remaining in the preliminary chamber is forced into the mixingchamber. When the piston has reached its closed position, its leadingsurface forms part of the mixing chamber wall.

In order to avoid the formation of unnecessary recesses or protrusionsin the mixing chamber wall, the leading surface of the piston mayconveniently be shaped to correspond to the wall of the mixing chamber.This means that where a tubular mixing chamber is used, for example, theleading surface of the piston will have a concave form corresponding tothe radius of curvature of the mixing chamber. In this embodiment,however, it should be ensured that when dealing, for example, withtwo-component systems, the two feed passages open into the preliminarychamber precisely opposite one another since otherwise the dishing ofthe leading surface of the piston will mean that the passages are notopened simultaneously.

It is advantageous if the feed passages open into the auxiliary chamberon a line parallel to the axis of the mixing chamber. In this region,the dished leading surface of the piston displays a cutting edge andthis is particularly suitable for scraping away any residues of materialwhich may be left behind in the neighbourhood of the feed orifices.

In order to achieve particularly good mixing of the components inthe'preliminary chamber, conveniently the passages may open into thischamber substantially tangentially. This feature also ensures that, inthe event of any extreme pressure difference occurring in the feedpassages, there is no possibility of one component penetrating into thepassage through which the other arrives and reacting with this othercomponent to block the passage.

An addition increasein the rate of injection of the components into thepreliminary chamber can be achieved by forming the passages as nozzleswhere they open into the chamber.

In order to avoid possible adhesion of parts of the mixture which arealready reacting, it is advantageous to arrange for the piston and/orthe preliminary chamber to be coated with an adhesion-reducing layer.This layer can, in the case of polyurethane, for example, be ofpolytetrafluroethylene.

BRIEF DESCRIPTION OF Til-IE DRAWINGS The invention will now be furtherdescribed with reference to the drawings, in which:

FIG. 1 is a partial side sectional view of one form of apparatusaccording to the invention;

FIG. 2 is a section taken along the line II-II OF FIG.

FIG. 3 is a detail of FIG. 2 on an enlarged scale;

FIG. 4 is a plan view of one form of the auxiliary chamber of FIG. 1;

FIG. 5 is a plan view of a modified form of the preliminary mixingchamber of FIG. 1;

FIG. 6 is a partial side sectional view of another form of apparatusaccording to the invention; and

FIG. 7 is an end view of the worm of FIG. 6; and

FIG. 8 is another operative position of the apparatus of FIG. 6.

Referring to FIGS. 1 and 2, a rotating mixing and conveyor worm 2 isarranged in a mixing chamber 1. Into the mixing chamber 1 there opens apreliminary mixing chamber 3 in which an axially displaceable butnon-rotatable piston 4 is disposed. The leading surface 5 of the piston4 is shaped to accord with the curvature of the wall of the mixingchamber 1 (see FIG. 2). Into the preliminary chamber 3 there open twofeed passages 6 and 7 which, because they are arranged in the same planenormal to the axis of the piston, can be closed off simultaneously bythe latter when it moves in the chamber 3.

FIG. 3 is a fragmentary view of the preliminary mixing chamber 3. Thechamber is provided with a lining 8. The leading surface of the piston 4is similarly coated with a layer 9. These layers 8 and 9 are made of amaterail to which the mixture formed does not adhere.

In the form of preliminary mixing chamber 3 shown in FIG. 4, thepassages 6 and 7' open substantially tangentially into the preliminarychamber 3 so that an eddying motion is produced in this chamber, whichcontributes to the preliminary mixing of the components.

In order to still further improve the speed of the entering material,the passage 6" and 7" (FIG. 5) can be designed as nozzles 9 and 10respectively in the neighbourhood of their entry into the preliminarychamber 3. The nozzles 9 and 10 can either be formed directly in thepreliminary chamber wall or alternatively separately manufacturednozzles cna be inserted therein.

In the embodiment shown in FIGS. 6 and 7, a shut-off piston 11 isdisposed concentrically to a mixing and conveyor worm 12 and rotatablymounted thereon through ballbearings 13 and 14. The worm 12 is providedin the neighbourhood of the piston 11 with a helical thread 15 and aspiral 16 (se FIG. 7), these serving to produce a self-cleaning actionin the gap. The piston 11 is in turn assembled for displacement in ahousing 18, a roll pin 17 being provided. The piston is movable axiallywith the worm l2 and in the left-hand terminal position opens feedpassages 19 whilst in the right-hand terminal position it closes them(FIG. 8). In another embodiment of the concentrical piston 11 as shownin FIG.6, the axially movable piston is carried on a shaft extension ofthe worm l2 and is axially movable with respect to the worm 12 andthereby opening and closing the orifices 19.

What is claimed is:

1. Apparatus for mixing and conveying at least two materials comprisinga mixing chamber, agitating and conveying means in said mixing chamber,two feed passages communicating with said mixing chamber throughrespective orifices, and a common sealing piston movable by slidingflush over said orifices beteen an open and closed position respectivelyto open and close said orifices, the axes of said orifices lying in aplane normal to the direction of travel of said piston, said piston insaid open position thereof lying completely to one side of saidorifices.

2. Apparatus as claimed in claim 1 wherein said agitating and conveyingmeans is a worm.

3. Apparatus as claimed in claim 2 wherein said piston is carried on andaxially movable with said worm.

4. Apparatus as claimed in claim 1 including a preliminary chamberopening into said mixing chamber wherein said piston is movable in saidpreliminary chamber, wherein said orifices are formed in the walls ofsaid preliminary chamber, and wherein the leading surface of said pistonwhen in the position to close said orifices forms part of the wall ofsaid mixing chamber.

5. Apparatus as claimed in claim 4 wherein said preliminary chamber islocated below said mixing chamber.

6. Apparatus as claimed in claim 4 wherein at least one of the wall ofsaid preliminary chamber and the leading surface of said piston iscoated with a material to which the mixture formed in said preliminarychamber in use will not adhere.

7. Apparatus for mixing and conveying at least two materials comprisinga mixing chamber, agitating and conveying means in said mixing chamber,two feed passages communicating with said mixing chamber throughrespective orifices, and a common sealing piston movable to open andclose said orifices, the axes of said orifices lying in a plane normalto the direction of travel of said piston, including a preliminarychamber opening into said mixing chamber wherein said piston is movablein said preliminary chamber, wherein said orifices are formed in thewalls of said preliminary chamber, snd wherein the leading surface ofsaid piston when in the position to close said orifices forms part ofthe wall of said mixing chamber, wherein each of said feed passagesopens substantially tangentially to said preliminary chamber.

8. Apparatus for mixing and conveying at least two materials comprisinga mixing chamber, agitating and conveying means in said mixing chamber,two feed passages communicating with said mixing chamber throughrespective orifices, and a common sealing piston movable to open andclose said orifices, the axes of said orifices lying in a plane normalto the direction of travel of said piston, including a preliminarychamber opening into said mixing chamber wherein said piston is movablein said preliminary chamber, wherein said orifices are formed in thewalls of said preliminary chamber, and wherein the leading surface ofsiad piston when in the position to close said orifices forms part ofthe wall of said mixing chamber, wherein each of said feed passages isformed as a nozzle at its opening into said preliminary chamber.

9. Apparatus for mixing and conveying at least two materials comprisinga mixing chamber, two feed passages communicating with said mixingchamber through respective orifices, and a sealing member movable flushover said orifices beteen an open and closed position respectively toopen and to close said orifices, said orifices lying in a plane parallelto the direction of travel of said sealing member, said sealing memberin said open position thereof lying completely to one side of saidorifices.

10. Apparatus according to claim 9, wherein said sealing member is apiston.

11. Apparatus as claimed in claim 9, further comprising, agitating andconveying means disposed in said mixing chamber.

12. Apparatus as claimed in claim 11, wherein said agitating andconveying means is axially connected to said sealing member.

1. Apparatus for mixing and conveying at least two materials comprisinga mixing chamber, agitating and conveying means in said mixing chamber,two feed passages communicating with said mixing chamber throughrespective orifices, and a common sealing piston movable by slidingflush over said orifices beteen an open and closed position respectivelyto open and close said orifices, the axes of said orifices lying in aplane normal to the direction of travel of said piston, said piston insaid open position thereof lying completely to one side of saidorifices.
 2. Apparatus as claimed in claim 1 wherein said agitating andconveying means is a worm.
 3. Apparatus as claimed in claim 2 whereinsaid piston is carried on and axially movable with said worm. 4.Apparatus as claimed in claim 1 including a preliminary chamber openinginto said mixing chamber wherein said piston is movable in saidpreliminary chamber, wherein said orifices are formed in the walls ofsaid preliminary chamber, and wherein the leading surface of said pistonwhen in the position to close said orifices forms part of the wall ofsaid mixing chamber.
 5. Apparatus as claimed in claim 4 wherein saidpreliminary chamber is located below said mixing chamber.
 6. Apparatusas claimed in claim 4 wherein at least one of the wall of saidpreliminary chamber and the leading surface of said piston is coatedwith a material to which the mixture formed in said preliminary chamberin use will not adhere.
 7. Apparatus for mixing and conveying at leasttwo materials comprising a mixing chamber, agitating and conveying meansin said mixing chamber, two feed passages communicating with said mixingchamber through respective orifices, and a common sealing piston movableto open and close said orifices, the axes of said orifices lying in aplane normal to the direction of travel of saiD piston, including apreliminary chamber opening into said mixing chamber wherein said pistonis movable in said preliminary chamber, wherein said orifices are formedin the walls of said preliminary chamber, snd wherein the leadingsurface of said piston when in the position to close said orifices formspart of the wall of said mixing chamber, wherein each of said feedpassages opens substantially tangentially to said preliminary chamber.8. Apparatus for mixing and conveying at least two materials comprisinga mixing chamber, agitating and conveying means in said mixing chamber,two feed passages communicating with said mixing chamber throughrespective orifices, and a common sealing piston movable to open andclose said orifices, the axes of said orifices lying in a plane normalto the direction of travel of said piston, including a preliminarychamber opening into said mixing chamber wherein said piston is movablein said preliminary chamber, wherein said orifices are formed in thewalls of said preliminary chamber, and wherein the leading surface ofsiad piston when in the position to close said orifices forms part ofthe wall of said mixing chamber, wherein each of said feed passages isformed as a nozzle at its opening into said preliminary chamber. 9.Apparatus for mixing and conveying at least two materials comprising amixing chamber, two feed passages communicating with said mixing chamberthrough respective orifices, and a sealing member movable flush oversaid orifices beteen an open and closed position respectively to openand to close said orifices, said orifices lying in a plane parallel tothe direction of travel of said sealing member, said sealing member insaid open position thereof lying completely to one side of saidorifices.
 10. Apparatus according to claim 9, wherein said sealingmember is a piston.
 11. Apparatus as claimed in claim 9, furthercomprising, agitating and conveying means disposed in said mixingchamber.
 12. Apparatus as claimed in claim 11, wherein said agitatingand conveying means is axially connected to said sealing member.